During the refining of steel by the bottom-blown oxygen process, commonly referred to as the Q-BOP process, oxygen containing entrained particles of lime is blown upwardly through tuyeres that communicate with the vessel interior below the level of molten metal therein. Each tuyere is enclosed by a concentric pipe for the simultaneous injection of shielding fluid such as natural gas, propane or other liquid or gaseous hydrocarbon, which acts as a coolant and delays contact between oxygen and the molten metal adjacent the tuyere outlets to retard tuyere erosion.
Typically a Q-BOP vessel is provided with upwards of twelve tuyeres. The tuyeres are disposed such that their openings to the vessel interior define a diametral swath across the vessel bottom. In order to insure uniform distribution of oxygen and entrained lime to each tuyere, the materials are delivered to a distribution manifold that is secured to the vessel bottom and from which feeder lines extend to each of the respective tuyeres. The distribution manifold is a hollow cylindrical body that is divided into two vertically spaced portions that are mutually connected by an axial connector tube. The oxygen-lime suspension is supplied tangentially into the upper portion and induced by cyclonic action to enter the connector tube for delivery to the lower portion from whence it exits the manifold through feeder lines that connect with the manifold through radial openings in the wall thereof.
Distributor manifolds of the described type suffer from the disadvantage of having a relatively brief useful life caused by undue wear that occurs on the interior surface thereof due to the abrasive effect of the high velocity lime particles on the wall surface. The region of most acute wear occurs on that part of the interior wall located immediately downstream of the point of tangency of the inlet pipe and can be attributed to the pinch effect produced by the recirculated portion of the fluid suspension that does not flow into the connector tube during its first traverse of the manifold interior. The recirculated portion of the fluid suspension, in flowing past the tangential inlet opening to the manifold, causes a restriction in the fluid flow path of the entering stream which increases the flow velocity of the fluid suspension and thereby aggravates the abrasive effect the lime particles have on surface wear.
It is to the improvement of such distribution manifolds therefore that the present invention is directed.